ENVIRONMENT-CUBA: Slashing Use of Ozone-Depleting Gases

By Patricia Grogg Reprint | | Print |

Patricia Grogg

HAVANA, Sep 16 2002 (IPS) - Cuba has eliminated the use of methyl bromide on its famed tobacco plantations. The pesticide is one of several substances that deplete the Earth’s atmospheric ozone layer, a natural shield that protects all life on the planet from harmful ultraviolet (UV) rays.

Methyl bromide, which is also harmful to human health, has been completely replaced on the island’s tobacco fields with alternative pest-control methods, government officials said Monday, International Day for the Preservation of the Ozone Layer.

This represents the substitution of 80 percent of all methyl bromide utilised in Cuban farm activities, said the authorities.

Tobacco plants are now protected by predatory organisms using system that entails biological pesticides, primarily the Trichodermi fungus, and organic inputs like peat and rice husks.

The United Nations Industrial Development Organisation (UNIDO) financed the plan to replace methyl bromide, whose ability to destroy the three-oxygen ozone molecules is 50 times greater than that of the chlorofluorocarbons (CFCs) that were once used worldwide in refrigeration and aerosols.

Methyl bromide, a strong-action insecticide and fungicide, was applied to the fields of tobacco — one of Cuba’s main exports — at a dosage of 30 grams per square metre under a polyethylene blanket.

In the early 1980s, this Caribbean island used 400 tons of methyl bromide annually on tobacco plantations alone, according to official figures.

Upon penetrating the soil, the chemical eliminates fungi, weeds and numerous insect species, properties that made it popular for use as an insecticide in storehouses and shipments as well.

Methyl bromide, CFCs and halons are gases regulated by the Montreal Protocol, a United Nations-sponsored treaty that entered into force in 1987, setting a phase-out schedule for the production, use and trade of these ozone-depleting substances.

Cuba was one of the 180 countries that signed the Protocol. As a developing nation, it has until 2010 to eliminate CFCs and until 2015 to halt use of methyl bromide.

The treaty establishes a more rigorous phase-out timeline for the industrialised North, taking into account that poor countries need more time to accumulate the financial and technological resources to replace those substances.

The ozone layer, in the upper reaches of the atmosphere, known as the stratosphere, at 15 to 50 km above the Earth’s surface, is crucial for all life on the planet because it filters out excessive UV rays.

Overexposure to UV radiation can cause skin cancer and vision loss in humans and animals, and can damage plant life and crops. It also threatens marine flora and fauna.

Scientists warn that if the ozone layer were to disappear, the UV rays would annihilate all life on Earth.

It was in the early 1980s that experts noticed the ozone layer became thinner — almost to the point of disappearing — over Antarctica during the Southern Hemisphere summer. The thinning, which appears almost as a “hole”, was found to be the result of use of CFCs, although scientists knew about the effect of the gases on ozone since the 1970s.

The chlorine atoms in the CFCs rise rapidly to the upper atmosphere and split apart the unstable ozone molecules. The massive use of these gases in industry and other human activities produced the so-called ozone hole over Antarctica.

From 1997 to 2001, Cuba reduced its CFC use 20 percent, from 625 tons to 506 tons a year, says Nelson Espinosa Peña, director of the government’s Ozone Technical Office.

In compliance with the Montreal Protocol, the country cancelled all imports of CFC-based equipment and technology in 1999, which meant the island had to convert its factories producing home and commercial refrigerators.

Cuba is committed to reducing its CFC consumption to 312 tons annually by 2005, which is 50 percent less than in 1997, says Espinosa.

To do so, it has the backing of the United Nations Development Program (UNDP), which has already carried out nine CFC abatement projects on the island for a total of 1.6 million dollars, including setting up the Ozone Technical Office.

Other initiatives have been aimed at salvaging and recycling refrigerants and studying methods to eliminate CFCs from medical devices.

Furthermore, efforts are under way to convert the air conditioning systems of the major Cuban hospitals, said Pablo Mandeville, UNDP representative in Cuba.

The Atmospheric Physics Centre at the Meteorology Institute has been working since February on a project to predict the daily UV radiation index around the midday hours.

The data would be useful for the medical field, farming and tourism, and would let individuals know how much time they could be exposed to the sun without risk of burning, say experts from the Institute.

According to measurements made in recent years over Cuba and the rest of the tropical latitudes, the ozone layer there remains within its normal limits, and does not undergo the cyclical thinning that happens over the Earth’s poles.